Japan's Yamanaka wins Nobel for stem cell breakthrough

Update:The Nobel prize in physiology or medicine has been awarded jointly to John Gurdon and Shinya Yamanaka. The award was given for their work showing that mature cells can be reprogrammed into pluripotent stem cells. These cells can develop into any other cell in the body.

Original article, posted 15 December 2007

Last month, Shinya Yamanaka at Kyoto University showed he could transform adult skin cells into cells akin to human embryonic stem cells. The method, which involves inserting genetic material that makes the cells' development run backwards, opens the door to stem cells specific to patients, which could be used to repair damaged organs or fight diseases such as Parkinson's and diabetes - crucially, all without the need to destroy human embryos. Linda Geddes visited Yamanaka in Kyoto and found him excited at his breakthrough but concerned over its ethical implications.

How did you feel when you realised you had made human embryonic-like cells from skin cells?We were very surprised. We had started working on this more than a year ago, when we tried inserting four transcription factors, which regulate genes, into the skin cells. It didn't work at all. We did get some cells but they turned out to be tumour cells rather than the reprogrammed stem cells - known as induced pluripotent stem (iPS) cells - that we were hoping for. The first time we saw iPS cells was this July. What we had changed was minor stuff, like how to prepare the cells for the introduction of the foreign material, and how to culture the cells.

I felt very proud of my fellows and students who did the job: they were very patient. At the same time I felt kind of responsible for this technology we had developed because now everybody has the means to develop embryonic-like cells. And they can do it without any approval from the authorities.

Do you have concerns about this?In theory, our work means that you can generate germ cells from iPS cells, which could be very good news for the treatment of infertility. So it is good in that sense. But I can make eggs as well as sperm from my own male iPS cells. What if somebody took those sperm and eggs from a single person and fertilised them? The result would not be a clone because of the way cells divide during sexual reproduction - the fertilised egg would not be genetically identical to the original iPS cells - but it would be something very strange and dangerous. At this time there are no guidelines or rules that would prevent this. This kind of fertility technology is still very difficult, so we don't have to worry about it too much at the moment. But now that everybody can generate these cells, it could become dangerous.

Do you think the technology you're developing is moving too fast for regulators to keep up?The technology has certainly moved faster than we expected. We don't feel guilty, but we do feel slightly responsible. I don't think we need the same level of regulation as for human embryonic stem cells, for example, because we are not using any embryos. But we do need to have some kind of rules or regulations in place.

Theoretically, scientists should now be able to make patient-specific iPS cells quite easily. But at the moment we have to use retroviruses to carry the foreign material into the cells, which could generate tumours. This is the same problem we have with gene therapy, so we wouldn't use this on patients yet. At this stage the iPS cells should be used only for testing out new drugs, until we find ways of making the changes without using a retrovirus.

However, it's possible that scientists in less regulated countries will offer these cells to people as a therapy for spinal cord injuries, for example. The patients may say they don't care about the risk of tumours and I am very afraid of that. In a sense I would feel responsible [if something went wrong] because we started this technology.

Are there any other scenarios that could raise ethical dilemmas?I'm not sure whether we should try to make eggs from male iPS cells and vice versa. In theory, two men could use this technology to have a baby, because you could take skin cells and use them to make an egg.

However, compared to embryonic stem cells I really think the issues are smaller. The potential of these cells is remarkable: in theory, you can make any cell in the body. I cannot say that the technology is free from escalation, but at least it could avoid the use of human embryos, and that makes it a big step forward.

Who do you think should be responsible for deciding what is ethically acceptable?These are very difficult decisions, and I think that society should make them. It should not be scientists. They can find it difficult to think like the person on the street, and instead may see it simply as a good opportunity. We scientists can be involved in the decision-making process, but I think unless society is comfortable with the therapy it should not go ahead.

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"I would feel responsible because we started this technology" (Image (Yamanaka in 2012): Aflo/Rex Features)